'EmbryoGlue' did not improve pregnancy rates in two studies

New evidence suggests that a widely debated IVF add-on does not increase clinical pregnancy rates.

'EmbryoGlue' is a type of embryo transfer medium, a liquid used during IVF to deliver the embryo into the uterus, which is enriched in a naturally occurring molecule known as hyaluronan. It is commonly offered as an additional-cost option during fertility procedures, in the hope that it may increase chances of success. However, a new retrospective cohort study found no improvement in pregnancy rate per IVF cycle between women who opted for standard or hyaluronan-enriched transfer medium (HETM).

'These findings contribute real-world evidence to the ongoing debate regarding the clinical utility of EmbryoGlue', write Dr Pelin Coştur Filiz and Professor Serdar Filiz from Kocaeli University, Turkey, in their paper published in Archives of Gynecology and Obstetrics.

Hyaluronan is present in high concentrations in the female reproductive tract, and in vitro experiments have shown it may contribute to embryos attaching to cells from the lining of the uterus. As such, its use in transfer medium has been considered a promising option to improve embryo implantation.

The unblinded retrospective study included 335 embryo transfer cycles in women aged 18-43: one group (171 transfers) used HETM, and the other a standard medium. The primary outcome was clinical pregnancy per transfer cycle, confirmed by blood tests and ultrasound exams. The two groups reported the same pregnancy rate (56.7 percent), demonstrating no overall benefit for HETM.

To examine whether certain subpopulations of women could benefit from the add-on, the HETM and standard medium groups were further divided based on embryo transfer type, embryo developmental stage, patient age, and number of previous attempts. Statistical analyses showed no significant differences in pregnancy rates between cycles using HETM or standard medium for these subgroups.

However, the researchers stress that the lack of observed benefit should not be interpreted as HETM being harmful. Furthermore, they suggest that further randomised trials should be conducted, particularly with live birth as the primary outcome (a factor not reported in this study).

Previous research investigating the impact of HETM has had mixed results, with meta-analyses sometimes suggesting a small overall benefit on clinical pregnancy and live birth rates. However, several recent studies have also shared findings that do not support the routine use of HETM in the clinic. For instance, in research presented at the 2026 American Society for Reproductive Medicine, technology company Nexpring Health and IVF laboratories Ovation Fertility reported that HETM was not associated with any improvement in implantation rates across 5661 frozen embryo transfer cycles. 

'Implantation is a complex process, and the most important parameters are embryo quality, euploidy and the quality of the uterine lining,' said Dr Nirvika Singh Sharma, associate laboratory director at Ovation Fertility San Antonio, and author of the study. 'In our study, we found that hyaluronan-enriched transfer medium just adds cost, without clinical gain.'

The UK fertility regulator, the Human Fertilisation and Embryology Authority, rates HETM 'amber' for improving the chances of live birth. That means that 'there is conflicting moderate/high quality evidence – in some studies the add-on has been found to be effective, but in other studies it has not'.